Digital lighting technologies, i.e. illumination based on semiconductor light sources, such as light-emitting diodes (LEDs), offer a viable alternative to traditional fluorescent, HID, and incandescent lamps. Functional advantages and benefits of LEDs include high energy conversion and optical efficiency, durability, lower operating costs, and many others. Recent advances in LED technology have provided efficient and robust full-spectrum lighting sources that enable a variety of lighting effects in many applications. Some of the fixtures embodying these sources feature a lighting module, including one or more LEDs capable of producing different colors, e.g. red, green, and blue, as well as a processor for independently controlling the output of the LEDs in order to generate a variety of colors and color-changing lighting effects.
Coded light (CL) systems generally comprise a plurality of lights within each of which is embedded a unique identifier or code. The invisible identifier or code can be embedded in light sources such as LEDs, as well as incandescent, halogen, fluorescent, and high-intensity discharge lamps. The identifier is based on modulation of visible light of the light source or by placing an additional infrared source in or with the light source and modulating that light emitted by this infrared source. LEDs are particularly well-suited for CL systems since they allow for high modulation bandwidth and frequency.
The unique identifier or code emitted by the light source can be utilized by a wide variety of tools and applications, including the identification of one or more specific light sources in the presence of numerous light sources, which in turn enables applications such as lighting manipulation and modification schemes. Further, information about the spatiotemporal location of the identified light source can either be separately associated with the identified light source's identifier, or can be directly embedded into the code transmitted by the coded light source. Coded light systems can be established in any location where a receiver capable of detecting coded light can be used, including but not limited to shopping malls, homes, office buildings, tunnels, subways, parking garages, and other locations.
As urbanization continues, more and larger indoor and/or underground environments will be built for shopping, parking, traffic, living, and so forth. Many such environments may alter, weaken and/or block global positioning system (GPS) signals, making navigation with mobile computing devices such as smart phones difficult. Those same environments may lack natural sunlight, and therefore may be lit with artificial lighting. Technology exists that enables sources of that artificial light to emit locational information that may be used by mobile computing devices for navigational purposes. However, a local network connection (e.g., Wi-Fi) may be required for the mobile computing device to associate a particular light source with a particular location. Further, such systems may not provide sufficient information for a mobile computing device to determine its precise location with sufficient accuracy.
Thus, there is a need in the art for light-based navigation and positioning technology that does not require a mobile computing device to connect to a local (e.g., wireless) network, and that is more accurate than existing approaches.